RFR: JDK-8062806 Remove unused build/make files

[Tim Bell]

Hi Magnus:
> Some files have been left in the build system, even though they are 
> not used (anymore).
>>
>> common/bin/boot_cycle.sh common/bin/compare-objects.sh is not needed 
>> anymore. The first was a crude replacement for the bootcycle-images 
>> target, and the second was only at use while the modern build system 
>> was developed.
>>
>> common/autoconf/config.h.in and common/autoconf/spec.sh.in both 
>> generate files in the $BUILD top directory which is not used. 
>> config.h was never used at all, and spec.sh was support for 
>> compare-objects.sh.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8062806
>> WebRev: 
>> http://cr.openjdk.java.net/~ihse/JDK-8062806-remove-unused-build-files/webrev.01
>>
>> /Magnus
>
> I noticed that I had missed to remove a reference to spec.sh in 
> Main.gmk. Harmless, but it should go away. Updated webrev:
>
> http://cr.openjdk.java.net/~ihse/JDK-8062806-remove-unused-build-files/webrev.02 
>

Looks good to me.

Tim